TADD-1 Assembly and Operation Manual
Six Channel RF Distribution Amplifier
Revised: 5 April 2014
©2005-14 Tucson Amateur Packet Radio Corporation
Introduction
NOTE: This is an update to the 2007 version of the manual that collects and hopefully corrects some
additional information (including the change from the MAX477 to the AD8055 amplifier chip), and
also provides some new performance information.
The TADD-1 is a six channel RF distribution amplifier. Its primary purpose is to allow one frequency source
(typically a frequency standard) to drive several loads (typically the "external reference" input of frequency
counters or other test equipment) with high isolation. The input frequency can range from 500 kHz to 30
MHz.
While the signal from a frequency standard is normally in the range of 0 to +13 dBm, an adjustable gain
control allows the TADD-1 to be used with a wide range of input signal levels. The maximum output signal
is approxi12.7 dBm into 50 ohms (2.75 volts peak-to-peak, or 0.97 volt RMS). Maximum output
voltage into a high impedance load is slightly higher. A jumper allows the input signal to be terminated in 50
ohms, or to operate at high impedance (approximately 47 kohms).
Each RF input and output on the TADD-1 is transformer coupled to minimize the possibility of ground loops.
In addition, the connectors are capacitively coupled to ground to further improve isolation (and allow
operation with signals riding on DC bias).
The TADD-1 includes a fused and reverse-polarity protected 9 volt regulator. The supply voltage can range
from 11.5 to 24 volts. Current drain will depend on the output loads, but is typically in the range of 60 to 150
milliamps.
See the "Performance" section for further details.
